Abstract: The present disclosure discloses a multilayer annular pore nickel-cobalt-aluminum precursor and a preparation method and a positive electrode material thereof. The precursor D50 is 8 to 20 ?m. It may be seen from a section diagram that there is a plurality of layers of annular pores in a secondary spherical particle structure, and a average porosity value of the section with a single particle or a plurality of particles is 6% to 14%. A co-precipitation reaction of nickel-cobalt mixed salt solution, alkali-aluminum solution, a complexing agent, and a precipitating agent is performed, a pH value and a concentration of aluminum solution at each stage are strictly controlled, and then working procedures of solid-liquid separating, washing, drying, mixing, sieving, and demagnetizing are performed to obtain the multilayer annular pore nickel-cobalt-aluminum precursor.

Abstract: The present disclosure discloses a gradient single-crystal positive electrode material, which has a chemical formula of LiNixCoyA1-x-yO2@mLiaZbOc, wherein 0<x<1, 0<y<1, 0<x+y<1, 0<m<0.05, 0.3<a?10, 1?b<4, and 1?c<15, A is at least one of Mn, Zr, Sr, Ba, W, Ti, Al, Mg, Y, and Nb, and Z is at least one of B, Al, Co, W, Ti, Zr, and Si. The atomic ratio of the content of Co on the surface of the single-crystal positive electrode material particle to the content of Ni+Co+A on the surface is greater than 0.4 and less than 0.8, and the atomic ratio of Co at a depth 10% of the radius from the surface of the single crystal positive electrode material particle is not less than 0.3; and the single-crystal positive electrode material particle has a roundness of greater than 0.4, and is free from sharp corners.

Abstract: The present disclosure discloses a gradient single-crystal positive electrode material, which has a chemical formula of LiNixCoyA1-x-yO2@mLiaZbOc, wherein 0<x<1, 0<y<1, 0<x+y<1, 0<m<0.05, 0.3<a?10, 1?b<4, and 1?c<15, A is at least one of Mn, Zr, Sr, Ba, W, Ti, Al, Mg, Y, and Nb, and Z is at least one of B, Al, Co, W, Ti, Zr, and Si. The atomic ratio of the content of Co on the surface of the single-crystal positive electrode material particle to the content of Ni+Co+A on the surface is greater than 0.4 and less than 0.8, and the atomic ratio of Co at a depth 10% of the radius from the surface of the single crystal positive electrode material particle is not less than 0.3; and the single-crystal positive electrode material particle has a roundness of greater than 0.4, and is free from sharp corners.